implemented mailer

.gitignore

@@ -21,4 +21,4 @@ go.work
 .idea
 .DS_Store
 .env
-/db-data/
+/app/

Dockerfile

@@ -3,6 +3,9 @@ FROM alpine:latest
 
 RUN mkdir /app
 
-COPY apiApp /app
+COPY apiApp /app/apiApp
+COPY .env /app/.env
+
+WORKDIR /app
 
 CMD ["/app/apiApp"]

Makefile.windows

@@ -0,0 +1,28 @@
+SHELL=cmd.exe
+API_APP_BINARY=apiApp
+
+## up: starts all containers in the background without forcing build
+up:
+    @echo Starting Docker images...
+    docker-compose up -d
+    @echo Docker images started!
+
+## up_build: stops docker-compose (if running), builds all projects and starts docker compose
+up_build: build_app
+    @echo Stopping docker images (if running...)
+    docker-compose down
+    @echo Building (when required) and starting docker images...
+    docker-compose up --build -d
+    @echo Docker images built and started!
+
+## down: stop docker compose
+down:
+    @echo Stopping docker compose...
+    docker-compose down
+    @echo Done!
+
+## build_app: builds the app binary as a linux executable
+build_broker:
+    @echo Building app binary...
+    chdir . && set GOOS=linux&& set GOARCH=amd64&& set CGO_ENABLED=0 && go build -o ${API_APP_BINARY} ./cmd/api
+    @echo Done!

README.md

@@ -1 +1,72 @@
-# genesis-api-project
+# Genesis API Project
+
+This service implements the following API:
+
+## API Endpoints
+
+### `GET` /rate
+
+This endpoint returns the current `USD to UAH` exchange rate using the Coinbase API.
+
+#### Parameters
+
+``No parameters``
+
+#### Response Codes
+
+```
+200: Returns the actual USD to UAH exchange rate.
+400: Invalid status value.
+```
+
+---
+
+### `POST` /subscribe
+
+This endpoint adds an email address to the database and automatically subscribes it to the USD to UAH exchange rate newsletter.
+
+_The code includes the ability to subscribe to other rates for future development, but this functionality is not currently used to fulfill the requirements._
+
+#### Parameters
+
+``email`` **string** (formData): The email address to be added to the database and the mailing list.
+
+#### Response Codes
+
+```
+200: The email address is added to the database and subscribed to the mailing list.
+409: The email address already exists.
+```
+
+_Not mentioned in the task, but arose during the development process:_
+```
+400: The provided data (such as email address) is invalid.
+500: Internal error status.
+```
+
+---
+
+### `POST` /sendEmails
+
+This endpoint sends the current `USD to UAH` exchange rate to subscribed email addresses using goroutines.
+
+#### Parameters
+
+``No parameters``
+
+#### Response Codes
+
+```
+200: Emails were sent.
+```
+
+## Usage:
+
+- Using Makefile
+```
+git clone https://github.com/vladyslavpavlenko/genesis-api-project.git
+cd genesis-api-project
+make up_build
+```
+
+Now you can reach an API using [`http://localhost:8080/`](http://localhost:8081/).

cmd/api/main.go

@@ -3,6 +3,7 @@ package main
 import (
 	"fmt"
 	"github.com/vladyslavpavlenko/genesis-api-project/internal/config"
+	"github.com/vladyslavpavlenko/genesis-api-project/internal/mailer"
 	"log"
 	"net/http"
 )
@@ -17,8 +18,9 @@ func main() {
 		log.Fatal()
 	}
 
-	log.Printf("Running on port %d", webPort)
+	mailer.ScheduleEmails(app.EmailConfig, app.DB)
 
+	log.Printf("Running on port %d", webPort)
 	srv := &http.Server{
 		Addr:    fmt.Sprintf(":%d", webPort),
 		Handler: routes(&app),

cmd/api/setup.go

@@ -3,6 +3,7 @@ package main
 import (
 	"errors"
 	"fmt"
+	"github.com/joho/godotenv"
 	"github.com/vladyslavpavlenko/genesis-api-project/internal/config"
 	"github.com/vladyslavpavlenko/genesis-api-project/internal/handlers"
 	"github.com/vladyslavpavlenko/genesis-api-project/internal/models"
@@ -16,7 +17,11 @@ import (
 var counts int64
 
 func setup(app *config.AppConfig) error {
-	// Connect to the database and run migrations
+	err := godotenv.Load()
+	if err != nil {
+		log.Fatalf("Error loading .env file: %v", err)
+	}
+
 	db, err := connectToDB()
 	if err != nil {
 		log.Fatal(err)
@@ -29,6 +34,16 @@ func setup(app *config.AppConfig) error {
 
 	app.DB = db
 	app.Models = models.New(db)
+
+	app.EmailConfig = config.EmailConfig{
+		Email:    os.Getenv("GMAIL_EMAIL"),
+		Password: os.Getenv("GMAIL_PASSWORD"),
+	}
+
+	if app.EmailConfig.Email == "" || app.EmailConfig.Password == "" {
+		log.Fatal("Missing email configuration in environment variables")
+	}
+
 	repo := handlers.NewRepo(app)
 	handlers.NewHandlers(repo)
 

docker-compose.yml

@@ -12,7 +12,9 @@ services:
       POSTGRES_PASSWORD: password
       POSTGRES_DB: emails
     volumes:
-      - ./db-data/postgres/:/var/lib/postgresql/data/
+      - ./app/db-data/postgres/:/var/lib/postgresql/data/
+      - /etc/timezone:/etc/timezone:ro
+      - /etc/localtime:/etc/localtime:ro
 
   api-app:
     build:
@@ -21,8 +23,13 @@ services:
     ports:
       - "8080:8080"
     restart: always
+    env_file:
+      - .env
     deploy:
       mode: replicated
       replicas: 1
+    volumes:
+      - /etc/timezone:/etc/timezone:ro
+      - /etc/localtime:/etc/localtime:ro
     environment:
       DSN: "host=postgres port=5432 user=postgres password=password dbname=emails sslmode=disable timezone=UTC connect_timeout=5"

go.mod

@@ -12,8 +12,13 @@ require (
 	github.com/jinzhu/inflection v1.0.0 // indirect
 	github.com/jinzhu/now v1.1.5 // indirect
 	github.com/joho/godotenv v1.5.1 // indirect
+	github.com/robfig/cron/v3 v3.0.1 // indirect
+	github.com/toorop/go-dkim v0.0.0-20201103131630-e1cd1a0a5208 // indirect
+	github.com/xhit/go-simple-mail/v2 v2.16.0 // indirect
 	golang.org/x/crypto v0.14.0 // indirect
 	golang.org/x/text v0.13.0 // indirect
+	gopkg.in/alexcesaro/quotedprintable.v3 v3.0.0-20150716171945-2caba252f4dc // indirect
+	gopkg.in/gomail.v2 v2.0.0-20160411212932-81ebce5c23df // indirect
 	gorm.io/driver/postgres v1.5.7 // indirect
 	gorm.io/gorm v1.25.10 // indirect
 )

go.sum

@@ -18,14 +18,24 @@ github.com/jinzhu/now v1.1.5/go.mod h1:d3SSVoowX0Lcu0IBviAWJpolVfI5UJVZZ7cO71lE/
 github.com/joho/godotenv v1.5.1 h1:7eLL/+HRGLY0ldzfGMeQkb7vMd0as4CfYvUVzLqw0N0=
 github.com/joho/godotenv v1.5.1/go.mod h1:f4LDr5Voq0i2e/R5DDNOoa2zzDfwtkZa6DnEwAbqwq4=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/robfig/cron/v3 v3.0.1 h1:WdRxkvbJztn8LMz/QEvLN5sBU+xKpSqwwUO1Pjr4qDs=
+github.com/robfig/cron/v3 v3.0.1/go.mod h1:eQICP3HwyT7UooqI/z+Ov+PtYAWygg1TEWWzGIFLtro=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
 github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+github.com/toorop/go-dkim v0.0.0-20201103131630-e1cd1a0a5208 h1:PM5hJF7HVfNWmCjMdEfbuOBNXSVF2cMFGgQTPdKCbwM=
+github.com/toorop/go-dkim v0.0.0-20201103131630-e1cd1a0a5208/go.mod h1:BzWtXXrXzZUvMacR0oF/fbDDgUPO8L36tDMmRAf14ns=
+github.com/xhit/go-simple-mail/v2 v2.16.0 h1:ouGy/Ww4kuaqu2E2UrDw7SvLaziWTB60ICLkIkNVccA=
+github.com/xhit/go-simple-mail/v2 v2.16.0/go.mod h1:b7P5ygho6SYE+VIqpxA6QkYfv4teeyG4MKqB3utRu98=
 golang.org/x/crypto v0.14.0 h1:wBqGXzWJW6m1XrIKlAH0Hs1JJ7+9KBwnIO8v66Q9cHc=
 golang.org/x/crypto v0.14.0/go.mod h1:MVFd36DqK4CsrnJYDkBA3VC4m2GkXAM0PvzMCn4JQf4=
 golang.org/x/text v0.13.0 h1:ablQoSUd0tRdKxZewP80B+BaqeKJuVhuRxj/dkrun3k=
 golang.org/x/text v0.13.0/go.mod h1:TvPlkZtksWOMsz7fbANvkp4WM8x/WCo/om8BMLbz+aE=
+gopkg.in/alexcesaro/quotedprintable.v3 v3.0.0-20150716171945-2caba252f4dc h1:2gGKlE2+asNV9m7xrywl36YYNnBG5ZQ0r/BOOxqPpmk=
+gopkg.in/alexcesaro/quotedprintable.v3 v3.0.0-20150716171945-2caba252f4dc/go.mod h1:m7x9LTH6d71AHyAX77c9yqWCCa3UKHcVEj9y7hAtKDk=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/gomail.v2 v2.0.0-20160411212932-81ebce5c23df h1:n7WqCuqOuCbNr617RXOY0AWRXxgwEyPp2z+p0+hgMuE=
+gopkg.in/gomail.v2 v2.0.0-20160411212932-81ebce5c23df/go.mod h1:LRQQ+SO6ZHR7tOkpBDuZnXENFzX8qRjMDMyPD6BRkCw=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
 gorm.io/driver/postgres v1.5.7 h1:8ptbNJTDbEmhdr62uReG5BGkdQyeasu/FZHxI0IMGnM=
 gorm.io/driver/postgres v1.5.7/go.mod h1:3e019WlBaYI5o5LIdNV+LyxCMNtLOQETBXL2h4chKpA=

internal/config/config.go

@@ -7,6 +7,13 @@ import (
 
 // AppConfig holds the application config.
 type AppConfig struct {
-	DB     *gorm.DB
-	Models models.Models
+	DB          *gorm.DB
+	Models      models.Models
+	EmailConfig EmailConfig
+}
+
+// EmailConfig holds the email configuration.
+type EmailConfig struct {
+	Email    string
+	Password string
 }

internal/handlers/handlers.go

@@ -4,7 +4,9 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+	"github.com/vladyslavpavlenko/genesis-api-project/internal/mailer"
 	"github.com/vladyslavpavlenko/genesis-api-project/internal/models"
+	"github.com/vladyslavpavlenko/genesis-api-project/internal/rate"
 	"net/http"
 	"strings"
 	"time"
@@ -31,16 +33,16 @@ type subscriptionBody struct {
 
 // GetRate gets the current USD to UAH exchange rate.
 func (m *Repository) GetRate(w http.ResponseWriter, r *http.Request) {
-	rate, err := getRate("USD", "UAH")
+	price, err := rate.GetRate("USD", "UAH")
 	if err != nil {
-		_ = m.errorJSON(w, errors.New("error calling Coinbase API"), http.StatusServiceUnavailable)
+		_ = m.errorJSON(w, errors.New("error calling Coinbase API"), http.StatusBadRequest) // http.StatusServiceUnavailable
 		return
 	}
 
 	rateResp := rateResponse{
 		BaseCurrencyCode:   "USD",
 		TargetCurrencyCode: "UAH",
-		Price:              rate,
+		Price:              price,
 	}
 
 	// Send response
@@ -140,5 +142,5 @@ func (m *Repository) Subscribe(w http.ResponseWriter, r *http.Request) {
 
 // SendEmails handles sending emails to all the subscribed emails.
 func (m *Repository) SendEmails(w http.ResponseWriter, r *http.Request) {
-
+	mailer.SendEmails(m.App.EmailConfig, m.App.DB)
 }

internal/handlers/helpers.go

@@ -3,7 +3,6 @@ package handlers
 import (
 	"encoding/json"
 	"errors"
-	"fmt"
 	"io"
 	"net/http"
 	"net/mail"
@@ -70,35 +69,3 @@ func validateEmail(email string) bool {
 	_, err := mail.ParseAddress(email)
 	return err == nil
 }
-
-// CoinbaseResponse is the Coinbase API response structure.
-type CoinbaseResponse struct {
-	Data struct {
-		Amount   string `json:"amount"`
-		Base     string `json:"base"`
-		Currency string `json:"currency"`
-	} `json:"data"`
-}
-
-// getRate returns the exchange rate between the base currency and the target currency using Coinbase API.
-func getRate(baseCurrencyCode string, targetCurrencyCode string) (string, error) {
-	url := fmt.Sprintf("https://api.coinbase.com/v2/prices/%s-%s/buy", baseCurrencyCode, targetCurrencyCode)
-	resp, err := http.Get(url)
-	if err != nil {
-		return "", fmt.Errorf("error making request: %v", err)
-	}
-	defer resp.Body.Close()
-
-	body, err := io.ReadAll(resp.Body)
-	if err != nil {
-		return "", fmt.Errorf("error reading the response body: %v", err)
-	}
-
-	var response CoinbaseResponse
-	err = json.Unmarshal(body, &response)
-	if err != nil {
-		return "", fmt.Errorf("error unmarshaling the response: %v", err)
-	}
-
-	return response.Data.Amount, nil
-}